JPH044468B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an ignition timing control device for an internal combustion engine.

It is well known that the octane number of gasoline has a strong correlation with knock resistance in internal combustion engines. In other words, the higher the octane number, the more difficult it is to knock. FIG. 1 shows the ignition timing-output shaft torque characteristics of an internal combustion engine using commercially available regular gasoline and premium gasoline (which has a higher octane number than regular gasoline). Point A is the knock limit point when regular gasoline is used, and point B is the knock limit point when premium gasoline is used. Knock occurs when the ignition timing is advanced beyond the knock limit point. According to FIG. 1, when premium gasoline is used, the ignition timing can be advanced to point B, so it is possible to improve the output shaft torque compared to when regular gasoline is used. FIG. 2 is an ignition timing characteristic diagram showing the ignition timing at points A and B in FIG. 1 with respect to the rotational speed of the internal combustion engine.

In an internal combustion engine with such characteristics, when regular gasoline and premium gasoline are mixed or used interchangeably, engine output can be increased by advancing the ignition timing according to the mixture ratio of regular gasoline and premium gasoline. It becomes possible to improve.

[Prior art]

By the way, in conventional ignition timing control devices, standard ignition timing characteristics are set only for a predetermined gasoline, such as regular gasoline, so when premium gasoline is mixed or converted, the standard ignition timing characteristics are set as they are. No improvement in engine output could be expected from the timing characteristics, and the standard ignition timing had to be reset to the advanced side in some way. Especially when using a mixture of regular gasoline and premium gasoline, depending on the mixture ratio, the second
As shown by the broken line in Figure c, there is a knock limit point between A and B, and the advance limit changes, so it is not easy to reset the reference ignition timing.
Furthermore, even if the reference ignition timing could be reset to the knock limit point, the knock limit point may fluctuate due to environmental conditions during engine operation, such as temperature and humidity, and may also change due to transients such as engine acceleration. Since knocks are likely to occur during operation, it has been impossible to avoid the occurrence of engine knocks.

[Summary of the invention]

The present invention has been made in view of the above points, and detects the occurrence of a knock using a knock sensor,
Based on the detected value, the standard ignition timing displacement amount that indicates the mixture ratio of regular gasoline and premium gasoline in use is determined, and the standard ignition timing is set to the advanced or retarded side accordingly. It determines the mixing ratio of regular gasoline and premium gasoline, adjusts the standard ignition timing to the optimal position, and also prevents knocks from occurring during sudden changes in environmental conditions or during transient operation. In other words, the ignition timing is retarded so as to immediately suppress the occurrence of knock.

[Embodiments of the invention]

Next, embodiments of the present invention will be described. FIG. 3 is a block diagram showing a first embodiment of the present invention.
In FIG. 3, reference numeral 1 denotes a knock sensor that is attached to the engine and detects a knock in the engine. Reference numeral 2 denotes a knock discriminating section for determining whether or not a knock has occurred from the output signal of the knock sensor 1, and is composed of a band pass filter BPF 21, a noise level detector 22, and a comparator 23. Bandpass filter 21
The input is connected to the knock sensor 1, and the output is connected to one comparison input of the comparator 23 and the noise level detector 22. The output of the noise level detector 22 is then connected to the other comparison input of the comparator 23. 3 is calculated from the output of the knock discriminator 2,
This is a retard control amount determination unit that determines a retard control amount for suppressing the occurrence of knocking in the engine, and includes an integrator 31,
It is composed of an A/D converter 32. Integrator 31
The integral input is connected to the output of the comparator 23, and the output is connected to the input of the A/D converter 32. Reference numeral 4 denotes a reference ignition timing displacement amount determination unit that determines the amount of displacement of the engine's reference ignition timing, and includes a pulse generator 41, a counter 42, a timer 43, and an up-down counter 4.
4, a timer 45, and a memory 46.
The input of pulse generator 41 is connected to the output of comparator 23, and the output is connected to the count input of counter 42. Timer 43 is connected to the reset input of counter 42. The up-count input of up-down counter 44 is connected to the output of counter 42, and the down-count input is connected to timer 45. The data input of the memory 46 is connected to the output of the up-down counter 44, and the data output is connected to the preset input of the up-down counter 44. 5 is a first ignition timing characteristic storage unit (hereinafter referred to as
ROM5) and 6 are second ignition timing characteristic storage units (hereinafter referred to as ROM6), in which ignition timing data is stored at addresses determined by the engine speed and load, respectively, as shown in Figure 4. .
7 is a first ignition timing calculator, which is composed of a proportional coefficient calculator 71, an interpolator 72, and a subtracter 73. The input of the proportional coefficient calculator 71 is connected to the output of the up-down counter 44, and converts the count contents of the up-down counter 44 into a proportional coefficient and outputs it. The interpolation calculator 72 has ROM5 and ROM6.
input the data and the output value of the proportional coefficient calculator 71, perform interpolation calculation between the data of ROM5 and ROM6 using the coefficient output from the proportional coefficient calculator 71,
The ignition timing data determined by the calculation is output. The subtracter 73 has two inputs connected to the interpolation calculator 73.
is connected to the output of the A/D converter 32, and the ignition timing data output from the interpolation calculator 73 is
The output value of the D converter 32 is subtracted, and ignition timing data shifted to the retarded side is output. 8 is a crank angle sensor that detects the crank rotation angle of the engine;
9 is a pressure sensor that detects the intake air pressure of the engine. 10 is a second ignition timing calculator, which calculates the engine speed from the output signal of the crank angle sensor 8, detects the engine load condition from the pressure sensor 9, and determines the engine speed and load from the output signal of the crank angle sensor 8. The value is converted into an address value, and the address value is output to ROM5 and ROM6. Then, the second ignition timing calculator 10 reads the ignition timing data output from the first ignition timing calculator (output of the subtractor 73),
Using the output signal of the crank angle sensor 8 as a reference, ignition timing is calculated from the output data of the first ignition timing calculator 7, and an ignition signal is output. Reference numeral 11 denotes a switching circuit that energizes the ignition coil 12 in synchronization with the ignition signal output from the second ignition timing calculator 10 and generates a high voltage necessary for igniting the internal combustion engine.

Next, the operation of the first embodiment will be explained.

FIG. 5 shows the operation of each part of the knock discriminating section 2. As shown in FIG.
The knock sensor 1 is a generally well-known vibration acceleration sensor that is attached to the cylinder block of an engine, converts the mechanical vibration of the engine into an electrical signal, and outputs a vibration wave signal as shown in FIG. 5a. . The bandpass filter 21 passes only the frequency component peculiar to the knock from the output signal of the knock sensor 1, suppresses noise components other than the knock, and
As shown in Figure b, a signal with a good S/N ratio is output. The noise level detector 22 can be composed of, for example, a half-wave rectifier circuit, an averaging circuit, an amplifier circuit, etc., and converts the output signal of the band-pass filter 21 (a in FIG. 5b) into a direct current by half-wave rectifying and averaging. It is converted into a voltage level, further amplified at a predetermined amplification degree, and then passed through a bandpass filter 21 as shown in FIG.
It outputs a DC voltage that is higher than the noise component of the output signal (a in FIG. 5b) and lower than the knock component. The comparator 23 is a bandpass filter 21
Compare the output signal of the noise level detector 22 (a in FIG. 5b) with the output signal of the noise level detector 22 (b in FIG. 5b),
When no knock occurs (section C in FIG. 4), the output signal of the bandpass filter 21 (section A in FIG. 5b)
is the output signal of the noise level detector 22 (Fig. 5b)
On the other hand, if a knock occurs (section D in FIG. 5), the output signal of the bandpass filter 21 (a in FIG. 5b) is output to the noise level detector 22. output signal (Fig. 5b, b)
In order to exceed this, a pulse train is output as shown in FIG. 5c. Therefore, the occurrence of a knock can be determined by the presence or absence of a pulse train (FIG. 5c) from the output of the comparator 23.

FIG. 6 shows the operation of each part of the retard control amount determination section 3 and the reference ignition timing displacement amount determination section 4. Integrator 31
integrates the pulse train (FIG. 6c) output from the comparator 23 and outputs an integrated voltage as shown in FIG. 6d. When the comparator 23 outputs a pulse train, it operates to increase the output voltage of the integrator 31 according to the pulse train, and when the pulse train is not output, it operates to decrease the output voltage of the integrator 31. Then, the output voltage of the integrator 31 is passed through the A/D converter 32 and controlled to retard the ignition timing by a first ignition timing calculator 7 and a second ignition timing calculator 10, which will be described later. Works as a voltage. That is, when a knock occurs, the pulse train output of the comparator 23 causes the output voltage of the integrator 31 to rise, retards the ignition timing, and suppresses the occurrence of a knock. Also, when the knocking stops occurring, the integrator 3
The output voltage of No. 1 falls and the ignition timing is advanced. Therefore, the retard control amount determining section 3 forms a closed loop control system that retards the ignition timing in real time when knock occurs, as shown by the output voltage of the integrator 31 in FIG. 6d. The rate of rise and fall of the output voltage of the integrator 31 is determined by the retard response due to knock occurrence and the closed loop control stability, but since instant control is required, it is set to a value with relatively fast response. .

Further, the reference ignition timing displacement determining section 4 determines the displacement of the reference ignition timing based on the degree of knock occurrence. The pulse generator 41 generates a pulse train as shown in FIG.
Outputs a pulse like this. In other words, the pulse generator 41 generates 1 pulse per ignition.
Outputs pulses. The output pulses of the pulse generator 41 are counted by a counter 42, and the count contents are shown in FIG. 6f. The timer 43 outputs a pulse at predetermined time intervals as shown in FIG. 6g, and the count value of the counter 42 is reset to zero by the pulse. Further, the output of the counter 42 becomes high level when the count value of the counter 42 exceeds a predetermined value (count value 3 in FIG. 6) as shown in FIG. 6h. That is, when a predetermined number of knocks occur within a predetermined time, the counter 42 outputs a high level signal. This is to calculate the knock occurrence rate. The up-down counter 44 counts up by one step when the output of the counter 42 rises from a low level to a high level. Further, the timer 45 outputs a pulse at predetermined time intervals as shown in FIG. 6j, and the pulse causes the up-down counter 44 to count down by one step. The count contents of the up-down counter 44 are shown in FIG. 6i. The memory 46 also stores the count value output by the up-down counter 44 when the ignition switch is turned off or when the power supply voltage drops, and stores the stored count value when the ignition switch is turned on or when the power supply voltage returns to the up-down counter. It is preset as a count value of 46.
In other words, the memory 46 allows the displacement amount of the reference ignition timing to be recorded and held even when the engine is stopped. As described above, the reference ignition timing displacement determining unit 4
calculates the knock occurrence rate, and if the occurrence rate exceeds a predetermined value, shifts the displacement amount (count value output by the up-down counter 44) to retard the reference ignition timing, and retards the displacement amount within a predetermined time. If there is no shift to the angle side, the displacement amount is shifted to the advance angle side. Therefore,
Similar to the retard control amount determining section 3, the reference ignition timing displacement determining section 4 also includes a first ignition timing calculator 7, which will be described later.
A closed-loop control system is formed through the second ignition timing calculator 10 to retard and advance the ignition timing when a knock occurs. However, the reference ignition timing displacement determining section 4 differs from the retard control amount determining section 3 in that the retard control amount determining section 3 retards the ignition timing in real time to suppress the occurrence of knocks by detecting knocks. On the other hand, in the reference ignition timing displacement amount determination unit 4, the knock occurrence rate is calculated by knock detection, and based on the calculation result, the reference ignition timing is shifted to the retard side or the advance side, thereby reducing the amount of gasoline used. This is to obtain a reference ignition timing that is compatible with the octane number of the engine. Therefore, the responsiveness of the reference ignition timing displacement amount determination unit 4 to the advance side and the retardation side is set to be relatively slower than the retardation/advancement responsiveness of the retard control amount determination unit 3. .

Next, the first ignition timing calculator 7 will be explained. A proportional coefficient calculator 71 converts the count value output from the up-down counter 44 into a proportional coefficient. Now, when the proportional coefficient calculator 71 inputs the count value N from the up-down counter 44, it divides this N by the preset maximum count value Nmax from the up-down counter 44, and calculates the division result proportionally. Let the coefficient k (=N/Nmax). Therefore, when premium gasoline is used, the knock limit point is relatively on the advance side, so the count value of the up-down counter 44 is approximately N=0, and the proportional coefficient is k=0. On the contrary, when regular gasoline is used, the knock limit point is relatively on the value angle side, so the count value of the up-down counter 44 is approximately N=Nmax, and the proportional coefficient is k.
=1. Furthermore, when a mixture of premium and regular gasoline is used, as shown in FIG. <Nmax, and the proportionality coefficient becomes 0<k<1. Therefore, it can be seen that the proportionality coefficient k is a coefficient indicating the mixing ratio of premium gasoline and regular gasoline.

On the other hand, the ROM5 and ROM6 receive address values corresponding to the engine speed and load from the second ignition timing calculator 10, and output the ignition timing data stored at the addresses to the interpolation calculator 72.
Now, set the ignition timing characteristics of ROM5 for premium gasoline, set the ignition timing data at the above address to θ _B , set the ignition timing characteristics of ROM6 for regular gasoline, and set the ignition timing data at the above address to θ B. If _A , the ignition timing characteristic of ROM5 is set to be the same as that of ROM6 or to the advanced side, so θ _A ≦ θ _B. Therefore, the interpolation calculator 72
performs proportional interpolation calculation between θ _A and θ _B using proportionality coefficient k. In other words, calculate θ _B - (θ _B - θ _A ) - k,
Letting the result be θ _C , θ _C is k between θ _B and θ _A :
The value is internally divided into (1-k). Therefore, when using premium gasoline, k = 0, so θ _C = θ _B ; when using regular gasoline, k = 1, so θ _C = θ _A , and when using a mixture of premium and regular gasoline, 0 < k < 1, so θ _A < θ _C <
_θB . Therefore, θ _C is a value that internally divides θ _A and θ _B based on the proportionality coefficient k indicating the mixing ratio of premium gasoline and regular gasoline, so even when premium gasoline and regular gasoline are mixed, By performing the above interpolation calculation, it is possible to obtain the optimum reference ignition timing according to the mixture ratio of premium and regular gasoline.

Furthermore, in the first ignition timing calculator 7,
The subtracter 73 subtracts the output value θ _D of the A/D converter 32 of the retard control amount determination unit 3 from the output value θ _C of the interpolation calculator 72, and ignites θ _E (=θ _C −θ _D ). Second period data
It is output to the ignition timing calculator 10. In other words, the retardation control amount is subtracted from the optimal reference ignition timing obtained by the interpolation calculator 72 in order to suppress the knocks that occur during transient operation of the engine or sudden changes in environmental conditions. This is to perform retard angle correction.

The second ignition timing calculator 10 uses the signal from the crank angle sensor 8 as a reference, and uses the ignition timing data (subtractor 7
The ignition timing is calculated based on the output value θ _E ) of No. 3, and an ignition signal is output. Since this is a well-known technique in ignition timing control devices, a description thereof will be omitted here.

Next, a second embodiment of the present invention will be described. This embodiment differs from the first embodiment in the configuration and connection of the reference ignition timing displacement determining unit 4 and the configuration of the first ignition timing calculator 7. FIG. 7 shows the configuration of this embodiment. In FIG. 7, 401 is a retard/advance determiner, 402 is a timer, 403 is a timer, 404 is an up-down counter, 405 is a memory, 701 is an adder, 702 is a proportional coefficient calculator, and 703 is an interpolator. The same reference numerals as in FIG. 3 indicate the same parts. In addition, an up-down counter 404, a memory 405, a proportional coefficient calculator 70
2. The interpolation calculator 703 is the same as the up-down counter 44, memory 46, proportional coefficient calculator 71, and interpolation calculator 72 of the first embodiment. The input of the retard/advanced angle determiner 401 is connected to the output of the retard control amount determining section 3 (the output of the A/D converter 32), and the output is two outputs: a lead angle determination output and a retard angle determination output. and A/D converter 32
The output value of is compared with a predetermined value, and a signal is output from the advance angle determination output or the retard angle determination output based on the comparison result. The input of the timer 402 is connected to the retard angle determination/output of the retard/advanced angle determiner 401, and the output is connected to the up count input of the up/down counter 404. The input of timer 403 is retarded.
It is connected to the lead angle determination output of the lead angle determiner 401, and the output is connected to the down count input of the up/down counter 404. The input of memory 405 is connected to the output of up-down counter 404, and the output is connected to the preset input of up-down counter 404. Adder 701 has two inputs, one of which is connected to the output of reference ignition timing displacement determining section 4 (output of up-down counter 404), and the other connected to the output of retard control amount determining section 3 (A/D conversion). 32 output). Then, the output of the adder 701 is connected to the input of the proportional coefficient calculator 702. Interpolation calculator 703 has ROM5 and ROM
6 and the output value of the proportional coefficient calculator 702 are input, and the calculation result is output to the second ignition timing calculator 10. The configuration of other parts is the same as that of the first embodiment.

FIG. 8 shows the operation of the reference ignition timing displacement determining section 4 in the second embodiment. Figure 8d shows integrator 3
1 output voltage is shown. The output of the A/D converter 32 is converted into a digital quantity. The retard/advance angle determiner 401 has two comparison reference values. One is a retard angle determination value, and the other is an advance angle determination value. Then, the output value of the A/D converter 32 is compared with the retard angle determination value and the advance angle determination value. 9th
The output mode of the retard/advanced angle determiner 401 is shown in the figure. Now, if the output value V of the A/D converter 32 is greater than or equal to the retard angle judgment value _V1 , the retard angle mode is set.
Set the retardation judgment output to a high level as shown in Fig. 8k,
If it is less than the lead angle judgment value V ₂ , it will be in advance angle mode and the lead angle judgment output will be set to high level as shown in Figure 8 1. If it is between V ₁ and V ₂ , it will be in stop mode and it will be in retard angle judgment. Both the output and advance angle judgment output become low levels. The timer 402 is a retard/advance determiner 401
The timer 403 outputs the output as shown in FIG. Then, a pulse is output as shown in FIG. 8n. FIG. 8p shows the count contents of the up-down counter. Up-down counter 404
counts up the output pulses of timer 402 and counts down the output pulses of timer 403. Therefore, when the output value of the retard control amount determining section 3 (the output value of the A/D converter 32) is larger than the retard determination value _V1 , the retard mode is entered and the count value of the up-down counter 404 is increased. , when it is smaller than the lead angle judgment value V ₂ , it becomes the lead angle mode and lowers the count value of the up-down counter 404 . Between V ₁ and V ₂ , the up-down counter 40
Holds the value of 4.

Next, the operation of the first ignition timing calculator 7 in the second embodiment will be explained. Adder 701 adds the output value of retard control amount determination section 3 (output value of A/D converter 32) and the output value of reference ignition timing displacement amount determination section 4 (output value of up-down counter 404). . The output value of the retard control amount determination section 3 indicates the retardation control amount for suppressing knock in real time, and the output value of the reference ignition timing displacement amount determination section 4 is used to adjust the reference ignition timing according to the octane number of the gasoline used. Indicate quantity. Therefore, the adder 701 outputs the sum of the retard control amount and the reference ignition timing adjustment amount. The proportional coefficient calculator 702 converts the output value of the adder 701 into a proportional coefficient, and the interpolator 703 interpolates the ignition timing data of ROM5 and ROM6 using the proportional coefficient output from the proportional coefficient calculator 702. This is similar to the description of the embodiment.

In this way, in the second embodiment, the reference ignition timing displacement amount determination section 4 determines retard or advance angle based on the output value of the retard control amount determination section 3, and determines the adjustment amount of the reference ignition timing. Further, ignition timing is calculated based on the sum of the output value of the retard control amount determination section 3 and the output value of the reference ignition timing displacement amount determination section 4.

Note that in the two embodiments described above, the reference ignition timing displacement determining section 4 and the first ignition timing calculator 7 can be interchanged between the first and second embodiments.

Further, in the above embodiment, each calculation control unit, that is, the reference ignition timing displacement determining unit 4, the ROM 5, the ROM
6. It is clear that the ignition timing calculation units 7, 10, etc. can be processed by software using a known computer.

〔Effect of the invention〕

As explained above, according to the present invention, when regular gasoline and premium gasoline are mixed and used, the knock sensor detects the knock, and based on that, calculates the displacement amount of the reference ignition timing, thereby adjusting the regular gasoline. The standard ignition timing characteristics can be automatically adjusted to the optimal ignition timing for premium blended gasoline, and the ignition timing can also be retarded in real time during transient engine operation or sudden changes in environmental conditions. Correct the ignition timing,
This has the effect of immediately suppressing the occurrence of knocks. Furthermore, the octane number is determined not simply by the presence or absence of knocks, but by the frequency of occurrence of the knocks, so that the octane number, that is, the amount of displacement in the ignition timing, can be accurately determined.

[Brief explanation of drawings]

Fig. 1 is an output shaft torque characteristic diagram of the engine, Fig. 2 is an ignition timing characteristic diagram of the engine, Fig. 3 is a block configuration diagram showing the first embodiment of the present invention, Fig. 4 is an ignition timing characteristic diagram, FIG. 5 is an explanatory diagram of the operation of the knock discriminator 2;
FIG. 6 is an explanatory diagram of the operation of the retard control amount determination section 3 and the reference ignition timing displacement amount determination section, and FIG.
FIG. 8 is an explanatory diagram of the operation of the reference ignition timing displacement determining unit 4 in the second embodiment, and FIG. 9 is an explanatory diagram of the output mode of the retard/advanced angle determiner 401. be. 1 is a knock sensor, 2 is a knock discrimination section, 3 is a retard control amount determining section, 4 is a reference ignition timing displacement amount determining section, 5 is a first ignition timing characteristic storage section, and 6 is a second ignition timing characteristic storage section. , 7 is a first ignition timing calculator, 8 is a crank angle sensor, 9 is a pressure sensor, 1
0 is a second ignition timing calculator, 11 is a switching circuit, and 12 is an ignition coil. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A knock sensor that detects a knock in an internal combustion engine;
Knock discriminating means for discriminating the presence or absence of knock occurrence from the output of the knock sensor; retard control amount determining means for determining a retard control amount for suppressing knock occurrence from the output of the knock discriminating means; the above-mentioned knock discriminating means; Reference ignition timing displacement determining means for calculating the knock occurrence frequency from the output of the retard control amount determining means, determining the octane number of the fuel used based on the knock occurrence frequency, and determining the displacement amount of the reference ignition timing of the engine; An ignition timing control device for an internal heat engine, comprising an ignition timing calculation means for determining the ignition timing of the engine according to the output of the reference ignition timing displacement amount determining means and the retard control amount determining means.